Radio frequency identification tag arranged for magnetically storing tag state information

ABSTRACT

A radio frequency identification tag system ( 10 ) utilizes a radio frequency identification tag ( 16 ) that includes stored tag information. The tag includes an antenna element ( 30 ) and a common electrode ( 28 ). The antenna element electrostatically receives an exciter signal ( 34 ) from a proximately-located electrostatic exciter ( 12 ). Upon receiving the exciter signal, the tag becomes energized, thereby causing it to generate a read signal ( 36 ) based on the stored tag information. The antenna element then electrostatically sends the read signal to a proximately-located reader ( 14 ), which detects the stored tag information. In addition, exactly one of the tag common electrode and the tag antenna element is arranged to magnetically store tag state information. The tag state information represents exactly one state of two possible states and is read by a proximately-located magnetic reader ( 18 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of prior U.S. patent application Ser. No.08/540,813, filed Oct. 11, 1995 by Ted Geiszler et al., now abandoned,and entitled “Remotely powered electronic tag and associatedexciter/reader and related method,” the disclosure of which priorapplication is hereby incorporated by reference, verbatim and with thesame effect as though such disclosure were fully and completely setforth herein. Also, this is a continuation-in-part of prior U.S. patentapplication Ser. No. 09/031,848 filed Feb. 27, 1998 by Victor Allen Vegaet al. and entitled “Radio frequency identification tag system usingtags arranged for coupling to ground,” now abandoned, the disclosure ofwhich prior application is hereby incorporated by reference, verbatimand with the same effect as though such disclosure were fully andcompletely set forth herein.

FIELD OF THE INVENTION

The present invention relates generally to the field of radio-frequencyidentification tags including, but not limited to, radio frequencyidentification tags arranged for magnetically storing tag stateinformation.

BACKGROUND OF THE INVENTION

Radio frequency identification tags and radio frequency identificationtag systems are known, and find numerous uses. For example, radiofrequency identification tags are frequently used for personalidentification in automated gate sentry applications protecting securedbuildings or areas. Information stored on the radio frequencyidentification tag identifies the person seeking access to the securedbuilding. Older systems require the person accessing the building toinsert or swipe a programmed identification tag into or through a readerfor the system to read the information from the identification tag. Aradio frequency identification tag conveniently reads the informationfrom the radio frequency identification tag at a small distance usingradio frequency (“RF”) data transmission technology eliminating theinserting or swiping operation. Most typically, the user simply holds orplaces the radio frequency identification tag near a base station, whichis coupled to a security system securing the building or area. The basestation transmits an excitation signal to the radio frequencyidentification tag that powers circuitry contained on the radiofrequency identification tag. The circuitry, responsive to theexcitation signal, communicates the stored information from the radiofrequency identification tag to the base station, which receives anddecodes the information. The read information is communicated to thesecurity system and, if appropriate, access is granted to theindividual. In general, radio frequency identification tags are capableof retaining and, in operation, transmitting a substantial amount ofinformation—sufficient information to uniquely identify individuals,packages, inventory and the like.

A typical technology for powering and reading a radio frequencyidentification tag is inductive coupling or a combination of inductivepower coupling and capacitive data coupling. Inductive coupling requiresincorporating a coil element into the radio frequency identificationtag. The coil element is excited (or “energized”) by an excitationsignal from a base station to provide power to the radio frequencyidentification tag circuitry. The radio frequency identification tagcoil, or a second tag coil, may be used to transmit and receive thestored information between the radio frequency identification tag to thebase station. Inductive coupling technology is relatively expensive,particularly for applications where it may be desirable to have adisposable radio frequency identification tag such as in an inventorymanagement application. Radio frequency identification tags relying oninductive coupling are also sensitive to orientation of the radiofrequency identification tag with respect to the base station since thefield created by the excitation signal must intersect the coil elementat substantially a right angle for effective coupling. Furthermore, readranges for inductively coupled devices are generally on the order ofseveral centimeters. Longer read distances are desirable, and forcertain applications, such as electronic animal identification, baggagetracking, parcel tracking and inventory management applications, arenecessary.

Other radio frequency identification tag technologies includemagnetically coupled, magnetically and electrostatically coupledtechnologies. While offering certain performance enhancements, and insome cases cost advantages, over inductive coupling technology, readranges with these other technologies remain unacceptably short. Forexample, in an electronic article surveillance (“EAS”) system, it isnecessary to read the radio frequency identification tag as it passesthrough a standard doorway. Similarly, because of the vast differencesin sizes of parcels and baggage an ability to read the radio frequencyidentification tag at a substantial distance is imperative. As will befurther appreciated orientation of the radio frequency identificationtag with respect to the base station can not be prearranged, andtherefore, can not be allowed to substantially effect read distances.Each of the mentioned technologies tends to be overly orientationsensitive.

Magnetic coupling technologies have found some success in EAS systems byproviding sufficiently large read ranges. For example, a magnetic stripand detection technology is available from 3M of St. Paul, Minn. (soldunder the product name “Tattle Tape”). The magnetic strips are small andthin thus allowing for easy insertion within the pages or spines ofbooks, jewel cases of CDs, and the like. Magnetic strip technology,however, is information limited. That is, the magnetic strips arecapable of providing only a single bit of information—typicallyindicating authorization yes/no for removal from the secured area.Magnetic strip technology is not capable of providing a sufficientamount of data for unique identification, and as such, is not suitablefor automated inventory applications.

Magnetic strip technology is also not suitable for applications wherethe protected media is magnetic in nature. The magnetic strip is codedand decoded by subjecting the strip to a magnetic field. Subjectingmagnetically recorded media, such as videotape, recorded audio tape,computer diskettes, and the like to magnetic fields may damage therecorded media.

Another important consideration for EAS system operation is read time. Aperson attempting to illegally remove an article from a secured area islikely not to pause while passing through a sensing area of thesurveillance system to allow the system time to read the surveillancetag. Magnetic strip technology offers fast read times; however, radiofrequency identification tag systems may not offer sufficiently fastread times, e.g., tag excitation, data transmission, data verificationand finally authorization, to be effective in EAS systems.

Still, radio frequency identification tag technology offers thesignificant advantage of storing and conveying sufficient information soas to uniquely identify persons, retail articles, parcels, packages,baggage and the like. However, radio frequency identification tagtechnology is limited in application by cost, read range and read time.Magnetic strip technology offers the advantage of long read range, andbased upon the limited amount of data conveyed, fast verification. Butbecause of the limited amount of information it is capable of conveying,magnetic strip technology is limited in application.

Thus, there is a need for an improved radio frequency identificationtag.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred exemplary embodiments of the invention are illustrated in theaccompanying drawings in which like reference numerals represent likeparts throughout.

FIG. 1 is a block diagram illustration of a radio frequencyidentification tag system in accordance with a preferred embodiment ofthe present invention.

FIG. 2 is a block diagram illustration of a radio frequencyidentification tag system in accordance with an alternate preferredembodiment of the present invention.

FIG. 3 is a block diagram illustration of a radio frequencyidentification tag system in accordance with an alternate preferredembodiment of the present invention.

FIG. 4 is a block diagram illustration of a radio frequencyidentification tag system in accordance with an alternate preferredembodiment of the present invention.

FIG. 5 is a block diagram illustration of a radio frequencyidentification tag in accordance with a preferred embodiment of thepresent invention.

FIG. 6 is a block diagram illustration of a radio frequencyidentification tag in accordance with a preferred embodiment of thepresent invention.

FIG. 7 is a block diagram illustration of a radio frequencyidentification tag in accordance with a preferred embodiment of thepresent invention.

FIG. 8 is a block diagram illustration of a radio frequencyidentification tag in accordance with a preferred embodiment of thepresent invention.

FIG. 9 is a block diagram illustration of a radio frequencyidentification tag in accordance with a preferred embodiment of thepresent invention.

FIG. 10 is a block diagram illustration of a radio frequencyidentification tag in accordance with a preferred embodiment of thepresent invention.

FIG. 11 is a block diagram illustration of a radio frequencyidentification tag in accordance with a preferred embodiment of thepresent invention.

FIG. 12 is a block diagram illustration of a radio frequencyidentification tag in accordance with a preferred embodiment of thepresent invention.

FIG. 13, FIG. 14 and FIG. 15 are schematic illustrations of a preferredembodiment of a radio frequency identification tag of the presentinvention, wherein the associated radio frequency identification siliconchip is attached to the tag electrodes by means of an interposser.

FIG. 16 is a schematic illustration of an alternate preferred embodimentof a radio frequency identification tag of the present invention,wherein the associated radio frequency identification silicon chip isdirectly attached to the tag electrodes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Radio frequency identification tag systems in accordance with preferredembodiments of the present invention utilize radio frequencyidentification tags having at least one electrode or antenna elementarranged for storing magnetically programmable tag state information.The programmed tag state information is quickly detectable within theradio frequency identification tag system and at an increased readdistance. In addition, the radio frequency identification tag includesat least one antenna element arranged for electrostatically receiving anexcitation signal and for electrostatically sending a read signal.Hence, performance is greatly enhanced in that authorization data, forexample, is quickly detected at far greater distances and identificationdata may be read from the radio frequency identification tag.

With reference to FIG. 1 of the drawings, a radio frequencyidentification tag system 10 includes: 1) a proximately-locatedelectrostatic exciter 12, 2) a proximately-located electrostatic reader14, 3) a radio frequency identification tag 16 and 4) aproximately-located magnetic reader 18. Electrostatic exciter 12includes an exciter common electrode 20 and an exciter antenna element22 coupled to an exciter circuit 21. Electrostatic reader 14 includes areader common electrode 24 and a reader antenna element 26 coupled to areader circuit 25. Radio frequency identification tag 16 includes a tagcommon electrode 28 and a tag antenna element 30 coupled to a tagcircuit 15. In the preferred implementation of the invention shown,exciter common electrode 20, reader common electrode 24 and tag commonelectrode 28 are coupled to ground 32.

Electrostatic exciter 12 provides an exciter signal 34. When radiofrequency identification tag 16 is proximate to electrostatic exciter12, exciter signal 34 is electrostatically coupled, through the air,from exciter antenna element 22 to tag antenna element 30. Radiofrequency identification tag 16 becomes energized based upon excitersignal 34. In accordance with the tag circuit 15 and stored taginformation of radio frequency identification tag 16, radio frequencyidentification tag 16 generates a read signal 38 containing some or allof the stored tag information, which is communicated from tag circuit 15to tag antenna element 30. Read signal 38 is electrostatically coupledfrom tag antenna element 30 to reader antenna element 26. Electrostaticreader 14 receives read signal 38, demodulates/decodes read signal 38 torecover the stored tag information therefrom and, as appropriate,communicates the stored tag information to other system elements (notshown). In a preferred implementation, read signal 38 is a reflectedsignal modulated by means of reflected load modulation based upon thestored tag information. It will be appreciated that other forms ofmodulation such as amplitude modulation (AM), frequency modulation (FM)or phase modulation (PM) may be used to convey the stored tagidentification.

Electrostatic exciter 12 may be advantageously constructed fromavailable tag exciter circuitry, such as for example, Motorola Indala'sASR-120 base station (part no. 05200-006 available from Motorola IndalaCorporation, 3041 Orchard Parkway, San Jose, Calif. 95134).

The ASR-120 device is adapted by forming and coupling a suitable exciterelectrode, for example a copper plate electrode, to one of the dipoleelectrode connections thereby forming the exciter antenna element 22.The other dipole electrode connection is coupled to earth therebyforming exciter common electrode 20. As the ASR-120 is also adaptable toreceive from a radio frequency identification tag the read signal, onewill appreciate that it may be further adapted to include the readerantenna element coupled to the read electrode connection.

Referring now to FIG. 5, in a read/write embodiment of the presentinvention radio frequency identification tag is advantageouslyconstructed from a TEMIC e5550 circuit chip (available from Temic NorthAmerica, Inc., Basking Ridge, N.J.). In this regard, and with referenceto FIG. 5, tag circuit 15 includes operatively coupled: 1) a rectifierand tag power circuit 50, 2) a clock circuit 52, 3) a write decodercircuit 54, 4) a memory 56, 5) a carrier signal and/or modulator circuit58 and 6) a controller 59. More particularly, tag antenna element 30 iscoupled to both rectifier and tag power circuit 50 and to carrier signaland/or modulator circuit 58, which in turn are respectfully coupled totag common electrode 28. Rectifier and tag power circuit 50 receivesexciter signal 34 via tag antenna element 30 and provides a directcurrent (dc) power supply 51. Exciter signal 34 is further coupled viarectifier and tag power circuit 50 to write decoder circuit 54 and clockcircuit 52. Clock circuit 52 provides a clock signal to each of writedecoder circuit 54, carrier signal and/or modulator circuit 58 andcontroller 59. Memory 56 retains the stored tag information and isaccessed by controller 59 and carrier signal and/or modulator 58. Uponexcitation, carrier signal and/or modulator circuit 58 generates readsignal 38 with the appropriate modulation and couples it to tag antennaelement 30. As described, read signal 38 is preferably a reflectedsignal modulated via load modulation. It will be appreciated, however,that other modulations, such as amplitude modulation (AM), frequencymodulation (FM) and phase modulation (PM) may be used to convey thestored tag information. In an alternate, read-only embodiment, theIndala I341 circuit chip available from the aforementioned MotorolaIndala Corporation may be used. It will be appreciated that in thisembodiment write decoder circuit 54 is not included.

Tag common electrode 28 is arranged to couple to ground. In a preferredembodiment (not shown), tag common electrode 28 may be arranged tocouple to a person or an animal. In this manner, tag common electrode 28is coupled to ground by means of the person or animal. Tag commonelectrode 28 may also be arranged to couple to an article (not shown).In this manner, tag common electrode 28 is coupled to ground by means ofthe article. In preferred applications, the article may be a loaned,leased or rented article, such as, for example, a video medium, an audiomedium, a computer program, a computer game, a video game or a book. Thearticle may also be a retail sales article such as, for example, an itemof clothing such as a dress, skirt, blouse, shirt, pair of jeans, coat,pants, or other garment.

In accordance with a preferred embodiment of the present invention,exactly one of the tag common electrode 28 and the tag antenna element30 is arranged for magnetically storing tag state information. The tagstate information is representative of exactly one state of two possiblestates. In this regard, exactly one of the tag common electrode 28 andthe tag antenna element 30 is formed from a magnetic strip. The magneticstrip is preferably a single bit EAS magnetic strip—a suitable magneticstrip material being the aforementioned 3M magnetic strip sold under theproduct name Tattle Tape. The magnetic strip is arranged as a single bitEAS strip for storing the magnetically programmable tag stateinformation. The magnetic strip is further arranged, as appropriate, asan effective tag common electrode 28 and/or a tag antenna element 30 foroperation as described.

As shown in FIG. 1, radio frequency identification tag system 10includes, in addition to proximately-located electrostatic exciter 12and proximately-located electrostatic reader 14, a proximately-locatedmagnetic reader 18. When radio frequency identification tag 16 isproximate magnetic reader 18, magnetic reader 18 reads the magneticallystored tag state information and conveys that information to EAS systemelements (not shown). Magnetic reader 18 provides an excitation signal19. Depending on the programming state of the magnetic strip, themagnetic strip will resonate producing a resonant signal 17. Resonantsignal 17 is detected by magnetic reader 18 to determine the tag stateinformation.

In a preferred embodiment, a first state of the two states may indicatethat an article is authorized for removal from the secured area while asecond of the two states may indicate that the article is unauthorizedfor removal from the secured area. The magnetically programmed nature ofthe tag state information permits high sensitivity detection. Undergeneral operation, the stored tag state information within radiofrequency identification tag 16 is used for asset identification and/orinventory control. For EAS, the high sensitivity of magnetic reader 18for detecting the magnetically-programmed tag state information provideseffective article security.

With continued reference to FIG. 1 and FIG. 5, in a read/writeembodiment, electrostatic exciter 12 is arranged to transmit atransmitted write signal 36 to radio frequency identification tag 16.Most preferably, transmitted write signal 36 is a modulation of excitersignal 34. Within tag circuit 15, write decoder circuit 54 decodes,i.e., demodulates, transmitted write signal 36 to recover the writeinformation and communicates the write information to controller 59.Controller 59 initiates a write operation during which the writeinformation is communicated to and retained within memory 56 as part ofthe stored tag information. The updated stored tag information forms thebasis for read signal 38. It will be appreciated that the transmittedwrite signal 36 may be an operation code or command. In this case, writedecoder circuit 54 is arranged to decode the operation code or command.

Referring to FIG. 7, an alternative preferred radio frequencyidentification tag 700 for use in radio frequency identification tagsystem 10 is shown. Radio frequency identification tag 700 includes atag common electrode 702 and a tag antenna element 704 coupled to a tagcircuit 706. Tag common electrode 702 is arranged to couple to ground.In a preferred embodiment (not shown), tag common electrode 702 may bearranged to couple to a person or an animal. In this manner, tag commonelectrode 702 is coupled to ground by means of the person or animal. Tagcommon electrode 702 may also be arranged to couple to an article (notshown). In this manner, tag common electrode 702 is coupled to ground bymeans of the article. In preferred applications, the article may be aloaned, leased, or rented article, such as, for example, a video medium,an audio medium, a computer program, a computer game, a video game or abook. The article may also be a retail sales article. Tag antennaelement 704 is arranged to electrostatically couple exciter signal 34.In a read/write embodiment, tag circuit 706 is preferably constructedfrom the aforementioned TEMIC e5550 circuit chip, while in a read-onlyapplication, tag circuit 706 is preferably constructed from the MotorolaIndala I341 circuit chip.

Each of tag common electrode 702 and tag antenna element 704 arepreferably arranged to magnetically store tag state information. The tagstate information is representative of exactly one state of two possiblestates. In this regard, each of tag common electrode 702 and tag antennaelement 704 is preferably formed from a magnetic strip. Each magneticstrip is arranged as a single bit EAS strip for storing the magneticallyprogrammable tag state information. When radio frequency identificationtag 700 is proximate magnetic reader 18, magnetic reader magneticallyreads the tag state information from tag common electrode 702 and tagantenna element 704.

With reference to FIG. 2 and FIG. 6, a radio frequency identificationtag system 201 includes: 1) a proximately-located electrostatic exciter12, 2) a proximately-located electrostatic reader 14, 3) a radiofrequency identification tag 200 and 4) a proximately-located magneticreader 18. Electrostatic exciter 12, electrostatic reader 14 andmagnetic reader 18 are arranged as discussed with respect to radiofrequency identification tag system 10 above. Radio frequencyidentification tag 200 includes a tag common electrode 202, a first tagantenna element 204 and a second tag antenna element 206 coupled to atag circuit 208. In the preferred implementation of the invention shown,exciter common electrode 20, reader common electrode 24 and tag commonelectrode 202 are coupled to ground 32.

Electrostatic exciter 12 provides an exciter signal 34. When radiofrequency identification tag 200 is proximate electrostatic exciter 12,exciter signal 34 is electrostatically coupled, through the air, fromexciter antenna element 22 to first tag antenna element 204. Radiofrequency identification tag 200 becomes energized based upon excitersignal 34. In accordance with the tag circuit 208 and stored taginformation of radio frequency identification tag 200, radio frequencyidentification tag 200 generates a read signal 210 containing some orall of the stored tag information, which is communicated from tagcircuit 208 to second tag antenna element 206. Read signal 210 iselectrostatically coupled from second tag antenna element 206 to readerantenna element 26. Electrostatic reader 14 receives read signal 210,demodulates/decodes read signal 210 to recover the stored taginformation therefrom and, as appropriate, communicates the stored taginformation to other system elements (not shown). In a preferredimplementation, read signal 210 is a transmitted signal modulated bymeans of an amplitude modulation (AM), a frequency modulation (FM) or aphase modulation (PM) to convey the stored tag identification.

Referring to FIG. 6, in a read/write embodiment of the present inventionradio frequency identification tag 200 is advantageously constructedfrom a derivative of the aforementioned TEMIC e5550 circuit chip. Inthis regard, and with reference to FIG. 6, tag circuit 208 includesoperatively coupled: 1) a rectifier and tag power circuit 250, 2) aclock circuit 252, 3) a write decoder circuit 254, 4) a memory 256, 5) acarrier signal and/or modulator circuit 258 and 6) a controller 260.More particularly, first tag antenna element 204 is coupled to rectifierand tag power circuit 250, and carrier signal and/or modulator circuit258 is coupled to second tag antenna element 206. Upon becomingenergized by exciter signal 34, rectifier and tag power circuit 250provides a direct current (dc) power supply 251. Exciter signal 34 isfurther coupled from first tag antenna element 204 via rectifier and tagpower circuit 250 to write decoder circuit 254 and clock circuit 252.Clock circuit 252 provides a clock signal to each of write decodercircuit 254, carrier signal and/or modulator circuit 258 and controller260. Memory 256 retains the stored tag information and is accessed bycontroller 260 and carrier signal and/or modulator circuit 258. Uponexcitation, carrier signal and/or modulator circuit 258 generates a readsignal 210 with an appropriate modulation and couples it to second tagantenna element 206. Preferably read signal 210 is a transmitted signalmodulated by means of at least one of an amplitude modulation, afrequency modulation or a phase modulation based upon the stored taginformation. Read signal 210 is electrostatically coupled from secondtag antenna element 206 to reader antenna element 26. In an alternate,read-only embodiment, the aforementioned Motorola Indala I341 circuitchip may be used. It will be appreciated that in this embodiment writedecoder circuit 254 is not included.

Tag common electrode 202 is arranged to couple to ground. In a preferredembodiment (not shown), tag common electrode 202 may be arranged tocouple to a person or an animal. In this manner, tag common electrode202 is coupled to ground by means of the person or animal. Tag commonelectrode 202 may also be arranged to couple to an article (not shown).In this manner, tag common electrode 202 is coupled to ground by meansof the article. In preferred applications, the article may be a loaned,leased or rented article, such as, for example, a video medium, an audiomedium, a computer program, a computer game, a video game or a book. Thearticle may also be a retail sales article.

In accordance with a preferred embodiment of the present invention,exactly one of tag common electrode 202, first tag antenna element 204and second tag antenna element 206 is arranged for magnetically storingtag state information. The tag state information is representative ofexactly one state of two possible states. In this regard, the exactlyone of tag common electrode 202, first tag antenna element 204 andsecond tag antenna element 206 is formed from a magnetic strip. Themagnetic strip is preferably a single bit EAS magnetic strip—a suitablemagnetic strip material being the aforementioned 3M magnetic strip soldunder the product name Tattle Tape. The magnetic strip is arranged as asingle bit EAS strip for storing the magnetically programmable tag stateinformation. The magnetic strip is further arranged, as appropriate, asan effective tag common electrode 202, a first tag antenna element 204or second tag antenna element 206 for operation as described.

As shown in FIG. 2, radio frequency identification tag system 201includes, in addition to proximately-located electrostatic exciter 12and proximately-located electrostatic reader 14, a proximately-locatedmagnetic reader 18. When radio frequency identification tag 200 isproximate magnetic reader 18, magnetic reader 18 reads the magneticallystored tag state information and conveys that information to EAS systemelements (not shown). Magnetic reader 18 provides an excitation signal19. Depending on the programming state of the magnetic strip, themagnetic strip will resonate producing a resonant signal 17. Resonantsignal 17 is detected by magnetic reader 18 to determine the tag stateinformation.

With continued reference to FIG. 2 and FIG. 6, in a read/writeembodiment, electrostatic exciter 12 is arranged to transmit atransmitted write signal 36 to radio frequency identification tag 200.Most preferably, transmitted write signal 36 is a modulation of excitersignal 34. Within tag circuit 208, write decoder circuit 254 decodes,i.e., demodulates, transmitted write signal 36 to recover the writeinformation and communicates the write information to controller 260.Controller 260 initiates a write operation during which the writeinformation is communicated to and retained within memory 256 as part ofthe stored tag information. The updated stored tag information forms thebasis for read signal 210. It will be appreciated that the transmittedwrite signal 36 may be an operation code or command. In this case, writedecoder circuit 254 is arranged to decode the operation code or command.

With reference to FIG. 8, an alternate preferred embodiment radiofrequency identification tag 800 shown. Radio frequency identificationtag 800 is arranged for use in, for example, radio frequencyidentification tag system 40. Radio frequency identification tag 800includes tag common electrode 802, first tag antenna element 804 andsecond tag antenna element 806 coupled to tag circuit 808. Tag commonelectrode 802 is arranged to couple to ground. In a preferred embodiment(not shown), tag common electrode 802 may be arranged to couple to aperson or an animal. In this manner, tag common electrode 802 is coupledto ground by means of the person or animal. Tag common electrode 802 mayalso be arranged to couple to an article (not shown). In this manner,tag common electrode 802 is coupled to ground by means of the article.In preferred applications, the article may be a loaned, leased or rentedarticle such as, for example, a video medium, an audio medium, acomputer program, a computer game, a video game or a book. The articlemay also be a retail sales article. First tag antenna element 804 isarranged for electrostatically coupling exciter signal 34. Second tagantenna element 806 is arranged for electrostatically sending readsignal 210. In a read/write embodiment, tag circuit 808 is preferablyconstructed from a derivative of the aforementioned TEMIC e5550 circuitchip, while in a read-only application, tag circuit 808 is preferablyconstructed from the Motorola Indala I341 circuit chip.

Exactly two of tag common electrode 802, first tag antenna element 804and second tag antenna element 806 are preferably arranged formagnetically storing tag state information. The tag state information isrepresentative of exactly one state of two possible states. In thisregard, the exactly two of tag common electrode 802, first tag antennaelement 804 and second tag antenna element 806 are preferably formedfrom a magnetic strip. Each magnetic strip is arranged as a single bitEAS strip for magnetically storing the tag state information. When radiofrequency identification tag 800 is proximate magnetic reader 18,magnetic reader magnetically reads the tag state information from theexactly two of tag common electrode 802, first tag antenna element 804and second tag antenna element 806 arranged to store magneticallyprogrammed tag state information. One will appreciate that anycombination of two of tag common electrode 802, first tag antennaelement 804 and second tag antenna element 808 may be arranged frommagnetically storing tag state information.

With reference to FIG. 9, an alternate preferred embodiment radiofrequency identification tag 900 shown. Radio frequency identificationtag 900 is arranged for use in, for example, radio frequencyidentification tag system 40. Radio frequency identification tag 900includes tag common electrode 902, first tag antenna element 904 andsecond tag antenna element 906 coupled to tag circuit 908. Tag commonelectrode 902 is arranged to couple to ground. In a preferred embodiment(not shown), tag common electrode 902 may be arranged to couple to aperson or an animal. In this manner, tag common electrode 902 is coupledto ground by means of the person or animal. Tag common electrode 902 mayalso be arranged to couple to an article (not shown). In this manner,tag common electrode 902 is coupled to ground by means of the article.In preferred applications, the article may be a loaned, leased or rentedarticle such as, for example, a video medium, an audio medium, acomputer program, a computer game, a video game or a book. The articlemay also be a retail sales article. First tag antenna element 904 isarranged for electrostatically coupling exciter signal 34. Second tagantenna element 906 is arranged for electrostatically sending readsignal 210. In a read/write embodiment, tag circuit 908 is preferablyconstructed from a derivative of the aforementioned TEMIC e5550 circuitchip, while in a read-only application, tag circuit 908 is preferablyconstructed from the Motorola Indala I341 circuit chip.

Tag common electrode 902, first tag antenna element 904 and second tagantenna element 906 are preferably arranged to magnetically store tagstate information. The tag state information is representative ofexactly one state of two possible states. In this regard, each of tagcommon electrode 902, first tag antenna element 904 and second tagantenna element 906 is preferably formed from a magnetic strip. Eachmagnetic strip is arranged as a single bit EAS strip for storing themagnetically programmable tag state information. When radio frequencyidentification tag 900 is proximate to magnetic reader 18, magneticreader 18 magnetically reads the tag state information from tag commonelectrode 902, first tag antenna element 904 and second tag antennaelement 906.

Referring now to FIG. 3, a radio frequency identification tag system 60includes 1) a electrostatic exciter 62, 2) a electrostatic reader 64, 3)a radio frequency identification tag 300 and 4) a magnetic reader 68.Electrostatic exciter 62 includes a first exciter antenna element 70 andsecond exciter antenna element 72 coupled to an exciter circuit 71.Electrostatic reader 64 includes a reader common electrode 74 and areader antenna element 76 coupled to a reader circuit 75. Radiofrequency identification tag 300 includes a first tag antenna element302 and a second tag antenna element 304 coupled to a tag circuit 306.In the preferred implementation of the invention shown reader commonelectrode 74 is coupled to ground 32. First tag antenna element 302 andsecond tag antenna element 304 are arranged for electrostaticallycoupling an exciter signal 82 and an exciter signal 84 from firstexciter antenna element 70 and second exciter antenna element 72,respectively.

More particularly, electrostatic exciter 62 provides an exciter signal82 and an exciter signal 84. When radio frequency identification tag 300is proximate to electrostatic exciter 62, exciter signal 82 iselectrostatically coupled, through the air, between first exciterantenna element 70 and first tag antenna element 302 and exciter signal84 is electrostatically coupled between exciter antenna element 72 andtag antenna element 304. Tag circuit 306 becomes energized based uponexciter signal 82 and exciter signal 84. In accordance with the storedtag information of radio frequency identification tag 300, tag circuit306 generates a read signal 86 containing some or all of the stored taginformation, which is communicated from tag circuit 306 to second tagantenna element 304. Read signal 86 is sent electrostatically fromsecond tag antenna element 304 to reader antenna element 76.Electrostatic reader 64 receives read signal 86, demodulates/decodesread signal 86 to recover the stored tag information therefrom and, asappropriate, communicates the stored tag information to other systemelements (not shown). In a preferred implementation, read signal 86 is areflected signal modulated by means of reflected load modulation basedupon the stored tag information. It will be appreciated that other formsof modulation such as amplitude modulation (AM), frequency modulation(FM) or phase modulation (PM) may be used to convey the stored tagidentification.

Electrostatic exciter 62 may be advantageously constructed fromavailable tag exciter circuitry, such as for example, the aforementionedMotorola Indala Corporation's ASR-120 base station. The ASR-120 deviceis adapted by forming and coupling a suitable exciter electrode, forexample a copper plate electrode, to each of the dipole electrodeconnections, thereby forming first exciter antenna element 70 and secondexciter antenna element 72. As the ASR-120 is also adaptable to receivefrom a radio frequency identification tag the stored tag information,one will appreciate that it may be further adapted to include the readerantenna element 76 coupled to the read electrode connection.

Radio frequency identification tag 300 may be arranged for attaching toan article (not shown). In preferred applications, the article may be aloaned, leased or rented article such as, for example, a video medium,an audio medium, a computer program, a computer game, a video game or abook. The article may also be a retail sales article. Radio frequencyidentification tag 300 may also be arranged for attaching to a person oran animal (not shown). In a read/write embodiment, tag circuit 306 ispreferably constructed from the aforementioned TEMIC e5550 circuit chip,while in a read-only application, tag circuit 306 is preferablyconstructed from the Motorola Indala I341 circuit chip.

In accordance with a preferred embodiment of the present invention,exactly one of first tag antenna element 302 and second tag antennaelement 304 is arranged for magnetically storing tag state information.The tag state information is representative of exactly one state of twopossible states. In this regard, exactly one of first tag antennaelement 302 and second tag antenna element 304 is formed from a magneticstrip. The magnetic strip is preferably a single bit EAS magneticstrip—a suitable magnetic strip material being the aforementioned 3Mmagnetic strip sold under the product name Tattle Tape. The magneticstrip is arranged as a single bit EAS strip for storing the magneticallyprogrammable tag state information. The magnetic strip is furtherarranged, respectively, as an effective first tag antenna element 302 oras a second tag antenna element 304 for operation as described.

As shown in FIG. 3, radio frequency identification tag system 60includes, in addition to proximately-located electrostatic exciter 62and proximately-located electrostatic reader 64 a proximately-locatedmagnetic reader 68. When radio frequency identification tag 300 isproximate magnetic reader 68, magnetic reader 68 reads the magneticallystored tag state information and conveys that information to EAS systemelements (not shown). Magnetic reader 68 provides an excitation signal69. Depending on the programming state of the magnetic strip, themagnetic strip will resonate producing a resonant signal 67. Resonantsignal 67 is detected by magnetic reader 68 to determine the tag stateinformation.

With continued reference to FIG. 3 in a read/write embodiment,electrostatic exciter 62 is arranged to transmit a transmitted writesignal 88 to radio frequency identification tag 300. Within tag circuit306, a write decoder decodes, i.e., demodulates, transmitted writesignal 88 to recover the write information and to, as appropriate,update the stored tag information. Transmitted write signal 88 may alsoinclude an operation code or a command. The updated stored taginformation forms the basis for read signal 86.

Referring to FIG. 10, an alternative preferred radio frequencyidentification tag 1000 for use in radio frequency identification tagsystem 60 is shown. Radio frequency identification tag 1000 includes afirst tag antenna element 1002 and a second tag antenna element 1004coupled to a tag circuit 1006. First tag antenna element 1002 and secondtag antenna element 1004 are arranged for electrostatically couplingexciter signal 82 and exciter signal 84, respectively. Radio frequencyidentification tag 1000 is also arranged for attaching to an article. Inreferred applications (not shown), the article may be a loaned, leasedor rented article, such as, for example, a video medium, an audiomedium, a computer program, a computer game, a video game or a book. Thearticle may further be a retail sales article. Radio frequencyidentification tag 1000 may also be arranged for attaching to a personor an animal (not shown). In a read/write embodiment, tag circuit 1006is preferably constructed from the aforementioned TEMIC e5550 circuitchip, while in a read-only application, tag circuit 1006 is preferablyconstructed from the Motorola Indala I341 circuit chip.

Each of first tag antenna element 1002 and second tag antenna element1004 are preferably arranged to magnetically store tag stateinformation. The tag state information is representative of exactly onestate of two possible states. In this regard, each of first tag antennaelement 1002 and second tag antenna element 1004 are preferably formedfrom a magnetic strip. Each magnetic strip is arranged as a single bitEAS strip for storing the magnetically programmable tag stateinformation. When radio frequency identification tag 1000 is proximatemagnetic reader 68, magnetic reader magnetically reads the tag stateinformation from first tag antenna element 1002 and second tag antennaelement 1004.

Referring now to FIG. 4, a radio frequency identification tag system 90includes 1) a proximately-located electrostatic exciter 62, 2) aproximately-located electrostatic reader 64, 3) a radio frequencyidentification tag 400 and 4) a proximately-located magnetic reader 68.Electrostatic exciter 62, electrostatic reader 64 and magnetic reader 68are arranged as discussed above with respect to radio frequencyidentification tag system 90. Radio frequency identification tag 400includes a first tag antenna element 402, a second tag antenna element404 and a third tag antenna element 406 coupled to a tag circuit 408. Inthe preferred implementation of the invention shown reader commonelectrode 74 is coupled to ground 32. First tag antenna element 402 andsecond tag antenna element 404 are arranged for electrostaticallycoupling an exciter signal 82 and an exciter signal 84 from firstexciter antenna element 70 and second exciter antenna element 72,respectively.

More particularly, electrostatic exciter 62 provides an exciter signal82 and an exciter signal 84. When radio frequency identification tag 400is proximate electrostatic exciter 62, exciter signal 82 iselectrostatically coupled, through the air, between first exciterantenna element 70 and first tag antenna element 402, and exciter signal84 is electrostatically coupled between second exciter antenna element72 and second tag antenna element 404. Tag circuit 408 becomes energizedbased upon exciter signal 82 and exciter signal 84. In accordance withthe stored tag information of radio frequency identification tag 400,tag circuit 408 generates a read signal 96 containing some or all of thestored tag information, which is communicated from tag circuit 408 tothird tag antenna element 406. Read signal 96 is sent electrostaticallyfrom third tag antenna element 406 to reader antenna element 76.Electrostatic reader 64 receives read signal 96, demodulates/decodesread signal 96 to recover the stored tag information therefrom and, asappropriate, communicates the stored tag information to other systemelements (not shown). In a preferred implementation, read signal 96 is atransmitted signal modulated by means of at least one of an amplitudemodulation (AM), a frequency modulation (FM) or a phase modulation (PM)to convey the stored tag identification.

Radio frequency identification tag 400 may be arranged for attaching toan article. In preferred applications, the article may be a loaned,leased or rented article, such as, for example, a video medium, an audiomedium, a computer program, a computer game, a video game or a book. Thearticle may also be a retail sales article. Radio frequencyidentification tag 400 may also be arranged for attaching to a person oran animal. In a read/write embodiment, tag circuit 408 is preferablyconstructed from a derivative of the aforementioned TEMIC e5550 circuitchip, while in a read-only application, tag circuit 408 is preferablyconstructed from the Motorola Indala I341 circuit chip.

In accordance with a preferred embodiment of the present invention,exactly one of the first tag antenna element 402, second tag antennaelement 404 and third tag antenna element 406 is arranged formagnetically storing tag state information. The tag state information isrepresentative of exactly one state of two possible states. In thisregard, the exactly one of first tag antenna element 402, second tagantenna element 404 and third tag antenna element 406 is formed from amagnetic strip. The magnetic strip is preferably a single bit EASmagnetic strip—a suitable magnetic strip material being theaforementioned 3M magnetic strip sold under the product name TattleTape. The magnetic strip is arranged as a single bit EAS strip forstoring the magnetically programmable tag state information. Themagnetic strip is further arranged, respectively, as an effective firsttag antenna element 402, second tag antenna element 404 or third tagantenna element 406 for operation as described.

As shown in FIG. 4, radio frequency identification tag system 90includes, in addition to proximately-located electrostatic exciter 62and proximately-located electrostatic reader 64 a proximately-locatedmagnetic reader 68. When radio frequency identification tag 400 isproximate magnetic reader 68, magnetic reader 68 reads the magneticallystored tag state information and conveys that information to EAS systemelements (not shown). Magnetic reader 68 provides an excitation signal69. Depending on the programming state of the magnetic strip, themagnetic strip will resonate producing a resonant signal 67. Resonantsignal 67 is detected by magnetic reader 68 to determine the tag stateinformation.

With continued reference to FIG. 4 in a read/write embodiment,electrostatic exciter 62 is arranged to transmit a transmitted writesignal 88 to radio frequency identification tag 400. Within tag circuit408, a write decoder decodes, i.e., demodulates, transmitted writesignal 88 to recover the write information and to, as appropriate,update the stored tag information. Transmitted write signal 88 may alsoinclude an operation code or a command. The updated stored taginformation forms the basis for read signal 96.

Referring to FIG. 11, an alternative preferred radio frequencyidentification tag 1100 for use in radio frequency identification tagsystem 90 is shown. Radio frequency identification tag 1100 includes afirst tag antenna element 1102, a second tag antenna element 1104 and athird tag antenna element 1106 coupled to a tag circuit 1108. First tagantenna element 1102 and second tag antenna element 1104 are arrangedfor electrostatically coupling exciter signal 82 and exciter signal 84.Third tag antenna element 1106 is arranged for sending read signal 96.Radio frequency identification tag 1100 is also arranged for attachingto an article (not shown). In preferred applications, the article may bea loaned, leased or rented article, such as, for example, a videomedium, an audio medium, a computer program, a computer game, a videogame or a book. The article may also be a retail sales article. Radiofrequency identification tag 1100 may also be arranged for attaching toa person or an animal (not shown). In a read/write embodiment, tagcircuit 1108 is preferably constructed from a derivative of theaforementioned TEMIC e5550 circuit chip, while in a read-onlyapplication, tag circuit 1108 is preferably constructed from theMotorola Indala I341 circuit chip.

Exactly two of first tag antenna element 1102, second tag antennaelement 1104 and third tag antenna element 1106 are preferably arrangedto magnetically store tag state information. The tag state informationis representative of exactly one state of two possible states. In thisregard, the exactly two of first tag antenna element 1102, second tagantenna element 1104 and third tag antenna element 1106 are preferablyformed from a magnetic strip. Each magnetic strip is arranged as asingle bit EAS strip for storing the magnetically programmable tag stateinformation. When radio frequency identification tag 1100 is proximatemagnetic reader 68, magnetic reader magnetically reads the tag stateinformation from the exactly two of first tag antenna element 1102,second tag antenna element 1104 and third tag antenna element 1106. Itwill be appreciated that any combination of two of first tag antennaelement 1102, second tag antenna element 1104 and third tag antennaelement 1106 may be arranged for magnetically storing tag stateinformation.

Referring to FIG. 12, an alternative preferred radio frequencyidentification tag 1200 for use in radio frequency identification tagsystem 90 is shown. Radio frequency identification tag 1200 includes afirst tag antenna element 1202, a second tag antenna element 1204 and athird tag antenna element 1206 coupled to a tag circuit 1208. First tagantenna element 1202 and second tag antenna element 1204 are arrangedfor electrostatically receiving exciter signal 82 and exciter signal 84.Third tag antenna element 1206 is arranged for sending transmitted writesignal 96. Radio frequency identification tag 1200 is also arranged forattaching to an article (not shown). In preferred applications, thearticle may be a loaned, leased or rented article, such as, for example,a video medium, an audio medium, a computer program, a computer game, avideo game or a book. The article may also be a retail sales article.Radio frequency identification tag 1200 may also be arranged forattaching to a person or an animal (not shown). In a read/writeembodiment, tag circuit 1208 is preferably constructed from a derivativeof the aforementioned TEMIC e5550 circuit chip, while in a read-onlyapplication, tag circuit 1208 is preferably constructed from theMotorola Indala I341 circuit chip.

Each of first tag antenna element 1202, second tag antenna element 1204and third tag antenna element 1206 are preferably arranged tomagnetically store tag state information. The tag state information isrepresentative of exactly one state of two possible states. In thisregard, each of first tag antenna element 1202, second tag antennaelement 1204 and third tag antenna element 1206 are preferably formedfrom a magnetic strip. Each magnetic strip is arranged as a single bitEAS strip for storing the magnetically programmable tag stateinformation. When radio frequency identification tag 1200 is proximatemagnetic reader 68, magnetic reader magnetically reads the tag stateinformation from each of first tag antenna element 1202, second tagantenna element 1204 and third tag antenna element 1206.

Fabrication of radio frequency identification (“RFID”) tags, inaccordance with the present invention, is now discussed. Using anadhesive-backed substrate, a dipole antenna comprising a first tagelectrode and a second tag electrode is constructed using a conductivemedium such as carbon ink, silver ink or a metallic strip, such as theaforementioned EAS Tattle Tape product supplied by 3M. The materialresistivity can be as high as several hundred ohms per square. Thedipole dimensions can be designed to accommodate a variety of formfactor applications. An RFID silicon chip which embodies the tag circuitis then attached to the first and second tag electrodes.

In an “interposser embodiment,” the RFID silicon chip is attached to thefirst and second tag electrodes by means of an interposser. Thisembodiment is best suited when used with metallic EAS strips. Asecondary peel-off adhesive is placed on top of the above assembly toprotect the contents and to allow adhesion to both the top and bottomsurfaces of interest (such as the case when placed between pages of abook). Once assembled, the product can be concealed within the confinesof the book's pages or on bindings or book covers. It can also bedisguised as a logo in a “smart label.” The interposser embodiment isshown in FIGS. 13-15.

Referring now to FIG. 13, there is shown a top view of an RFID tag 1300arranged in accordance with this interposser embodiment. As shown, theRFID tag 1300 includes a tag substrate 1304. Disposed on the substrate1304 is a first tag electrode 1306 and a second tag electrode 1308. Alsoshown is an interposser 1353, which interposser includes an RFID siliconchip 1302 (discussed with FIG. 14 below) and is arranged for couplingthe RFID silicon chip to the first tag electrode 1306 and the second tagelectrode 1308. (Since the back side of the interposser 1353 is shown inthis FIG. 13, the RFID silicon chip 1302 is not visible.)

Referring now to FIG. 14, there is shown an enlarged view of the frontside of the interposser 1353. As shown, the interposser 1353 includes asubstrate 1351. Disposed on the substrate is a first interposserconnecting pad 1314 and a second interposser connecting pad 1316. Inturn, disposed on the first interposser connecting pad 1314 and thesecond interposser connecting pad 16 is the RFID silicon chip 1302.

Referring now to FIG. 15, there is shown a side cross-section view ofthe RFID tag 1300, including a profile view of the interposser 1353. Asshown, the first interposser connecting pad 1314 and the secondinterposser connecting pad 1316 are respectively arranged to bond to thefirst tag electrode 1306 and the second tag electrode 1308 by means of asuitable conducting adhesive. As a result, the RFID silicon chip 1302couples to the first tag electrode 1306 and the second tag electrode1308 by means of the first interposser connecting pad 1314 and thesecond interposser connecting pad 1316, respectively.

As mentioned above, preferably the conductive media 1306 and 1308 areformed using a magnetic material, such as the magnetic strip productavailable from 3M under the product name Tattle Tape. In this manner,first tag electrode 1306 and second tag electrode 1308 may be arrangedto store tag state information. However, in applications not requiringthe additional sensitivity available using magnetic material to formboth first tag electrode 1306 and second tag electrode 1308, nonmagneticconductive medium, such as carbon or silver ink, may be used to formeither first tag electrode 1306 or second tag electrode 1308.

In an alternate “direct attachment embodiment,” the RFID silicon chip isdirectly attached to the first and second tag electrodes. Referring nowto FIG. 16, there is shown a side cross-section view of an RFID tag 1600arranged in accordance with this direct attachment embodiment. Similarto the RFID tag 1300 discussed with FIG. 13 above, the RFID tag 1600includes a tag substrate 1604, together with a first tag electrode 1606and a second tag electrode 1608 being disposed on the substrate 1604. Inturn, disposed on the first tag electrode 1606 is a first connecting pad1656. Similarly, disposed on the second tag electrode 1608 is a secondconnecting pad 1658. Finally, disposed on the first connecting pad 1656and the second connecting pad 1658 is an RFID silicon chip 1302′, whichchip is otherwise similar to the RFID silicon chip 1302 discussed withthe interposser embodiment and FIGS. 13-15 above. As a result, the RFIDsilicon chip 1302′ is directly attached (and coupled) to the first tagelectrode 1606 and the second tag electrode 1608. In this embodiment,the RFID silicon chip 1302′ can utilize flip chip technology withanisotropic or isotropic mediums, conductive adhesives or any otherconventional bonding technique.

In either the interposser embodiment of FIGS. 13-15 or the directattachment embodiment of FIG. 16, it will be appreciated that each offirst tag electrode (1306 or 1606) and second tag electrode (1308 or1608) may be arranged as a tag common electrode for coupling to groundor as a tag antenna element as the application requires. As well, firsttag electrode (1306 or 1606) and second tag electrode (1308 or 1608)serve to electrostatically couple signals to and from radio frequencyidentification tag (1300 or 1600) while further providing formagnetically storing tag state information. It will be appreciated thatonly one of the electrodes need be formed from a magnetic material, forcost considerations and where increased sensitivity is not required.Furthermore, as noted above, the magnetically programmed electrode tagstate information may be used for activating an EAS alarm, while storedtag information may be used to identify the article.

In summary, referring again to FIG. 1 and FIG. 2, there has beendisclosed a radio frequency identification tag system (10 or 201)including an electrostatic exciter 12, an electrostatic reader 14, atleast one radio frequency identification tag (16 or 200) and a magneticreader 18; the electrostatic exciter 12 including an exciter circuit 21,an exciter common electrode 20 and an exciter antenna element 22 coupledto the exciter circuit, the exciter common electrode arranged forcoupling to ground 32, the exciter circuit arranged for generating anexciter signal 30 and coupling the exciter signal to the exciter antennaelement, the exciter antenna element arranged for electrostaticallysending the exciter signal to the at least one radio frequencyidentification tag; the electrostatic reader including a reader circuit25 and a reader common electrode 24 and a reader antenna element 26, thereader common electrode arranged for coupling to ground, the readerantenna element arranged for electrostatically receiving a read signal(38 or 210) from the at least one radio frequency identification tag andcoupling the read signal to the reader circuit, the at least one radiofrequency identification tag including a stored tag information, and thereader circuit arranged for detecting the stored tag information.

Referring now to the radio frequency identification tag system 10depicted in FIG. 1, there has been disclosed a first embodiment of aradio frequency identification tag 16 including a tag circuit 15, a tagcommon electrode 28 and a tag antenna element 30 coupled to the tagcircuit, the tag common electrode arranged for coupling to ground, thetag antenna element arranged for electrostatically receiving the excitersignal 34 from the exciter antenna element and coupling the excitersignal to the tag circuit; the tag circuit arranged for becomingenergized based on the exciter signal, generating a read signal 38 andcoupling the read signal to the tag antenna element; the tag antennaelement arranged for electrostatically sending the read signal to thereader antenna element and the read signal being a reflected readsignal; and exactly one of the tag common electrode and the tag antennaelement being arranged to magnetically store tag state information suchthat the tag state information can be magnetically read by aproximately-located magnetic reader, the tag state informationrepresenting exactly one state of two possible states.

Referring now to the radio frequency identification tag system 201depicted in FIG. 2, there has been disclosed an alternate embodiment ofa radio frequency identification tag 200 including a tag circuit 208, atag common electrode 202, a first tag antenna element 204, and a secondtag antenna element 206 coupled to the tag circuit, the tag commonelectrode arranged for coupling to ground, the first tag antenna elementarranged for electrostatically receiving the exciter signal 34 from theexciter antenna element and coupling the exciter signal to the tagcircuit; the tag circuit arranged for becoming energized based on theexciter signal, generating a read signal 210 and coupling the readsignal to the second tag antenna element; the second tag antenna elementarranged for electrostatically sending the read signal 210 to the readerantenna element and the read signal being a transmitted read signal; andexactly one of the tag common electrode, the first tag antenna elementand the second tag antenna element being arranged to magnetically storetag state information such that the tag state information can bemagnetically read by a proximately-located magnetic reader, the tagstate information representing exactly one state of two possible states.

In further summary and referring again to FIG. 3 and FIG. 4, there hasbeen disclosed a radio frequency identification tag system (60 or 90)including an electrostatic exciter 62, an electrostatic reader 64, atleast one radio frequency identification tag (300 or 400) and a magneticreader 68; the electrostatic exciter 62 including an exciter circuit 71,a first exciter antenna element 70 and a second exciter antenna element72, the exciter circuit arranged for generating an exciter signal (82and 84) and coupling the exciter signal to the first exciter antennaelement and the second exciter antenna element, the first exciterantenna element and the second exciter antenna element arranged forelectrostatically sending the exciter signal to the least one radiofrequency identification tag; the electrostatic reader including areader circuit 75 and a reader common electrode 74 and a reader antennaelement 76, the reader common electrode arranged for coupling to ground,the reader antenna element arranged for electrostatically receiving aread signal (86 or 96) from the at least one radio frequencyidentification tag and coupling the read signal to the reader circuit,the at least one radio frequency identification tag including a storedtag information, and the reader circuit arranged for detecting thestored tag information.

Referring now to the radio frequency identification tag system 60depicted in FIG. 3, there has been disclosed an alternate embodiment ofa radio frequency identification tag 300 including a tag circuit 306, afirst tag antenna element 302 and a second tag antenna element 304coupled to the tag circuit, the first tag antenna element and the secondtag antenna element arranged for electrostatically receiving the excitersignal from the first exciter antenna element and the second exciterantenna element, respectively, and coupling the exciter signal to thetag circuit; the tag circuit arranged for becoming energized based onthe exciter signal, generating a read signal 86 and coupling the readsignal to the first tag antenna element; the first tag antenna elementarranged for electrostatically sending the read signal to the readerantenna element and the read signal being a reflected read signal; andexactly one of the first tag antenna element and the second tag antennaelement being arranged to magnetically store tag state information suchthat the tag state information can be magnetically read by aproximately-located magnetic reader, the tag state informationrepresenting exactly one state of two possible states.

Referring now to the radio frequency identification tag system 90depicted in FIG. 4, there has been disclosed an alternate embodiment ofa radio frequency identification tag 400 including a tag circuit 408, afirst tag antenna element 402, a second tag antenna element 404, and athird tag antenna element 406 coupled to the tag circuit, the first tagantenna element and the second tag antenna element arranged forelectrostatically receiving the exciter signal from the first exciterantenna element and the second exciter antenna element, respectively,and coupling the exciter signal to the tag circuit; the tag circuitarranged for becoming energized based on the exciter signal, generatinga read signal 96 and coupling the read signal to the third tag antennaelement; the third tag antenna element arranged for electrostaticallysending the read signal 96 to the reader antenna element and the readsignal being a transmitted read signal; and exactly one of the first tagantenna element, the second tag antenna element and the third tagantenna element being arranged to magnetically store tag stateinformation such that the tag state information can be magnetically readby a proximately-located magnetic reader, the tag state informationrepresenting exactly one state of two possible states.

Some advantages of radio frequency identification tags havingmagnetically programmed electrodes, in accordance with the presentinvention, as compared to prior tags, are now discussed.

To begin, radio frequency identification tags of the present inventionare less expensive than employing separate EAS and radio frequencyidentification technologies. In contrast to prior tags that did not usethe magnetic EAS material as an integral component of the radiofrequency identification embodiment, the present invention combinesthese two technologies in a single tag. As a result, the present tag'scomponent count is significantly reduced, thus its cost is reduced aswell.

Further, the present invention provides the user with significantly moreinformation than is provided by the single-bit magnetic EAS solutionalone.

Moreover, the present invention allows the user to continue usingexisting magnetic EAS systems with the additional benefit of assetmanagement provided by the integrated radio frequency identificationtechnology.

While various embodiments of a radio frequency identification tagarranged for magnetically storing tag state information, in accordancewith the present invention, have been described hereinabove, the scopeof the invention is defined by the following claims.

We claim:
 1. A radio frequency identification tag comprising: a tagcircuit; a tag common electrode; and a tag antenna element, wherein thetag common electrode and the tag antenna element are coupled to the tagcircuit, the tag common electrode is arranged for coupling to ground,the tag antenna element is arranged for capacitively receiving anexciter signal from an exciter and coupling the exciter signal to thetag circuit, the tag circuit is arranged for becoming energized based onthe exciter signal, generating a read signal and coupling the readsignal to the tag antenna element, the tag antenna element is arrangedfor capacitively sending the read signal to a reader, and at least oneof the tag common electrode and the tag antenna element is arranged formagnetically storing tag state information.
 2. The radio frequencyidentification tag of claim 1, wherein the tag common electrode isfurther arranged for coupling to an article.
 3. The radio frequencyidentification tag of claim 2, wherein the tag common electrode isfurther arranged for coupling to ground by means of the article.
 4. Theradio frequency identification tag of claim 3, wherein the article is aloaned, leased or rented article.
 5. The radio frequency identificationtag of claim 3, wherein the article is a retail sales article.
 6. Theradio frequency identification tag of claim 1, wherein the tag commonelectrode is arranged for coupling to an animal or a person, and whereinthe tag common electrode is further arranged for coupling to ground bymeans f the animal or the person.
 7. The radio frequency identificationtag of claim 1, wherein the tag antenna element is further arranged forreceiving a write signal from the exciter, the write signal comprisingwrite information, and the tag antenna element arranged for capacitivelycoupling the write signal to the tag circuit, the tag circuit furtherarranged for storing the write information as a stored tag information,the read signal being modulated by means of reflected load modulationbased on the stored tag information.
 8. The radio frequencyidentification tag of claim 7, wherein the read signal being furthermodulated b means of at least one of an amplitude modulation, afrequency modulation, or a phase modulation.
 9. A radio frequencyidentification tag comprising: a tag circuit; a tag common electrode; afirst tag antenna element; and a second tag antenna element, the tagcommon electrode, the first tag antenna element and the second tagantenna element is coupled to the tag circuit, the tag common electrodeis arranged for coupling to ground, the first tag antenna element isarranged for capacitively receiving an exciter signal from an exciterand coupling the exciter signal to the tag circuit, the tag circuit isarranged for becoming energized based on the exciter signal, generatinga read signal and coupling the read signal to the second tag antennaelement, the second tag antenna element is arranged for capacitivelysending the read signal to a reader, at least one of the tag commonelectrode, the first tag antenna element and the second tag antennaelement arranged for magnetically storing tag state information suchthat the tag state information can be magnetically read by a magneticreader, the tag state information comprising exactly one state of twopossible states.
 10. The radio frequency identification tag of claim 9,wherein the tag common electrode is arranged for coupling to an article,the tag common electrode is further arranged for coupling to ground bymeans of the article.
 11. The radio frequency identification tag ofclaim 10, wherein the article is a retail sales article.
 12. The radiofrequency identification tag of claim 9, wherein the tag commonelectrode is arranged for coupling to an animal or a person, the tagcommon electrode further arranged for coupling to ground by means of theanimal or the person.